Logical partitioning allows the establishment of a plurality of system images within a single physical machine or central processor complex (CPC). Each system image is capable of operating as if it was a separate computer system. That is, each logical partition can be independently reset, initially loaded with an operating system that may be different for each logical partition, and operate with different software programs using different input/output (I/O) devices.
Examples of logically partitioned computing systems are described in, for instance, Guyette et al., U.S. Pat. No. 4,564,903, entitled “Partitioned Multiprocessor Programming System”, issued on Jan. 14, 1986; Bean et al., U.S. Pat. No. 4,843,541, entitled “Logical Resource Partitioning Of A Data Processing System”, issued on Jun. 27, 1989; and Kubala, U.S. Pat. No. 5,564,040, entitled “Method And Apparatus For Providing A Server Function In A Logically Partitioned Hardware Machine”, issued on Oct. 8, 1996, each of which is hereby incorporated herein by reference in its entirety.
Commercial embodiments of logically partitioned systems include, for example, IBM S/390® processors with the Processor Resource/Systems Manager™ (PR/SM™) feature, which is described, for instance, in the IBM publication Processor Resource/Systems Manager Planning Guide, GA22-7236-04, March 1999, which is hereby incorporated herein by reference in its entirety.
One important aspect of a logically partitioned system is the management of workload running within the partitions of that system. In S/390 systems, for example, workload managers are used to manage the workload within and among the partitions. The workload managers attempt to balance the workload of the partitions by moving work to the physical resources of the system. In order to move the work, however, it is important to ensure that the data needed by the relocated work is at the moved location. This need often restricts the movement of work. Thus, although efforts have been made to balance workload within a logically partitioned system, further needs exist and further efforts are needed.